Their uselessness is part of what makes them a good store of value. Useful things get used up, so they don't last.Gold emerged as a standard in the past for good historical reason, and those reasons still apply today. It's rare, it doesn't rust or perish, and it is hard to forge. You can mix it with lesser metals, but that's relatively easy to detect by weighing and volume measurement. Gold in a standard form, eg coins, is even easier to validate. Arguably gold is even more likely to become the basis of an economy in future, because of its past. It has a track record. People know it works. They'll expect it.

I think in an initial crisis, people will hope it will end in a few weeks or months, and even uneducated ones will know they'll be able to sell gold for a decent value when its over. So there will be a viable gold economy quite quickly. There's no reason why that shouldn't last, as long as there are humans living above subsistence level to trade with.